• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1903-1905
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• 2005

다중 코어를 이용한 대전류용 고효율 변압기 개발을 위해 고주파 손실이 작고, 전기 비저항이 큰 자성재료와 최적의 코어 형상 및 권선 방법에 대한 연구개발과 최종적으로 고효율 다중 코어를 이용한 변압기를 개발하고 전원장치에 적용하여 동작특성을 평가하였다. 최소 손실 온도를 $90^{\circ}C$ 이하로 감소시켜 100 kHz에서 250kW/m3의 낮은 전력손실을 갖는 다중 코어를 이용하여 변압기를 제조하고, 제조된 변압기가 채용된 컨버터의 50A 출력 전류에서 측정된 변압기의 발열특성은 30분 이후 약 $58^{\circ}C$까지 증가하였으며, $30{\sim}80A$의 출력 전류에서 85% 이상의 고효율을 얻었다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.1
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• pp.61-65
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• 2017

In this paper a prototype of high frequency heating power supply system based on the high frequency heating principle is designed to take the place of acupuncture, moxibustion, warm dressing treatment and some other traditional physical therapy methods. Which possess the advantages of low cost, convenient, easy operation and good effect. The high frequency heating power supply can generate a pulse voltage of more than 1KV with 300KHz switching frequency to heat the patient's skin. The skin temperature can reach to $41{\sim}42^{\circ}C$. The peak current control method is used to maintain the skin temperature in the designed range. The design of the main circuit is based on the flyback converter topology. An easier and practical design method is proposed in this paper. The power supply system prototype is verified to be stable and reliable by both the simulation and experimental results.

• Resources Recycling
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• v.19 no.3
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• pp.24-32
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• 2010

In the present work, a new separation system with rotating rakes has been developed to separate the film-based plastics from the recyclable materials, and environment assessment is also carried out during operation of the device. Capacity of the device was about 5.3 ton/hr at a rakes rotation speed of 26.0 rpm (the number of rakes in the 1st, 2nd and 3rd trials were 39, 52 and 48, respectively) and a belt conveyor speed of 38.5m/min, which satisfied the initial design capacity (5.0 ton/hr). Recovery ratio and purity of the plastic films were 92.6% and 96.5%, respectively at a rotation speed of 28 rpm. The levels of noise, vibration and particulate emission were below material standard regulatory limits. Plastic refused fuel (RPF) was also prepared with the recovered films. The calorific value and chlorine content of the prepared RPF were 9,740 kcal/kg and 0.18%, respectively which satisfy the first grade quality specification of the Korean RPF standard. As a result of this work, recovery of energy resources from the municipal solid waste is possible by adopting the developed separation device.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.12
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• pp.1013-1019
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• 2014

Solid-liquid Phase Change Material(PCM) as a thermal control hardware for the electro-optical payload of low earth orbit satellite is numerically studied which can be substituted with Thermal Buffer Mass(TBM). The electro-optical module in LEO satellite is periodically work and high heat is dissipated during the imaging period, however, the design temperature range is very tight and sensitive. In order to handle this problem TBM is added and as a result the time constant of the module temperature increases. TBM is made of Al6010 and its mass directly affects the system design. To save the mass PCM is suggested in this study. The latent heat of melting or solidification is very high and small amount of PCM can play a role instead of TBM. The result shows that only 12% of TBM mass is enough to control the module temperature using PCM.

• Journal of IKEEE
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• v.20 no.1
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• pp.61-67
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• 2016

In this paper, a hardware design method is proposed for high speed high precision neutron radiation measurements. Our system is fabricated to use a high performance A/D Converter for digital data conversion of high precision and high speed analog signals. Using a neutron sensor, incident neutron radiation particles are detected; a precision microcurrent measurement module is also included: this module allows for more precise and rapid neutron radiation measurement design. The high speed high precision neutron measurement hardware system is composed of the neutron sensor, variable high voltage generator, microcurrent precision measurement component, embedded system, and display screen. The neutron sensor detects neutron radiation using high density polyethylene. The variable high voltage generator functions as a 0 ~ 2KV variable high voltage generator that is robust against heat and noise; this generator allows the neutron sensor to perform normally. The microcurrent precision measurement component employs a high performance A/D Converter to precisely and swiftly measure the high precision high speed microcurrent signal from the neutron sensor and to convert this analog signal into a digital one. The embedded system component performs multiple functions including neutron radiation measurement for high speed high precision neutron measurements, variable high voltage generator control, wired and wireless communications control, and data recording. Experiments using the proposed high speed high precision neutron measurement hardware shows that the hardware exhibits superior performance compared to that of conventional equipment with regard to measurement uncertainty, neutron measurement rate, accuracy, and neutron measurement range.

• Journal of the Korean Wood Science and Technology
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• v.40 no.3
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• pp.204-211
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• 2012

In this study, fast pyrolysis of pitch pine (Pinus rigida) was performed in a fluidized bed reactor under the temperature ranges between 400 and $550^{\circ}C$ at the residence time of 1.9 sec. Essential pyrolytic products (bio-oil, biochar, and gas) were produced and their yield was clearly influenced by temperature. The maximum yield of bio-oil was observed to 64.9 wt% (wet basis) at the temperature of $500^{\circ}C$. As pyrolysis temperature increased, the yield of biochar decreased from 36.8 to 11.1 wt%, while gas amount continuously increased from 16.1 to 33.0 wt%. Water content as well as heating value of bio-oils were obviously sensitive to the pyrolysis temperature. The water contents in the bio-oil clearly decreased from 26.1 ($400^{\circ}C$) to 11.9 wt% ($550^{\circ}C$), with increasing the fast pyrolysis temperature, while their higher heating values were increased from 16.6 MJ/kg to 19.3 MJ/kg. According to GC/MS analysis, 22 degradation compounds were identified from the bio-oils and 10 compounds were derived from carbohydrate, 12 compounds were derived from lignin.

• Journal of the Korea Convergence Society
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• v.7 no.6
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• pp.13-21
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• 2016

In this paper we are trying to explain the effect of temperature on polymer membrane exchange water electrolysis (PEMWE) and polymer membrane exchange fuel cell (PEMFC) simultaneously. A comprehensive studying approach is proposed and applied to a 50Watt PEM fuel cell system in the laboratory. The monitoring process is carried out through wireless LoRa node and gateway network concept. In this experiment, temperature sensor measure the temperature level of electrolyzer, fuel cell stack and $H_2$ storage tank and transmitted the measured value of data to the management control unit (MCU) through the individual node and gateway of each PEMWE and PEMFC. In MCU we can monitor the temperature and its effect on the performance of the fuel cell system and control it to keep the lower heating value to increase the efficiency of the fuel cell system. And we also proposed a mathematical model and operation algorithm for PEMWE and PEMFC. In this model, PEMWE gives higher efficiency at lower heating level where as PEMFC gives higher efficiency at higher heating value. In order to increase the performance of the fuel cell system, we are going to monitor, communicate and control the temperature and pressure of PEMWE and PEMFC by installing these systems in a building of university which is located in the southern part of Korea.

• Journal of the Korean Vacuum Society
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• v.20 no.4
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• pp.280-287
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• 2011

The heat temperature of a light emitting diode (LED) is investigated with the thermoelectric device (TED). The Peltier effect of the thermoelectric device is used to control the heat radiation and the junction temperature of high-power LEDs. For the typical specific current (350 mA) of high-power (1 W) LEDs, the LED temperature and the p-n junction temperature become $64.5^{\circ}C$ and $79.1^{\circ}C$, respectively. For 0.1~0.2 W driving power of TED, the LED temperature and the junction temperature are reduced to be $54.2^{\circ}C$ and $68.9^{\circ}C$, respectively. As the driving power of the TED increases over 0.2 W, the temperature of LED itself and the junction temperature are increased due to the heat reversed from the heat-sink to LED. As the difference of temperature between LED and the heat-sink is increased, the quantity of reversed heat becomes larger and it results to degrade the cooling capability of TED.

• Fire Science and Engineering
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• v.24 no.5
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• pp.136-141
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• 2010

The purpose of this study is to examine the structure and heat generation mechanism of low voltage switches used to turn on or off the power supply to an indoor lighting system and investigate how the fixtures and movable contacts of the switches are damaged depending on the types of energy sources in order to secure the judgment base for expected PL disputes. Based on the Korean Standard (KS) testing method for incombustibility, this study applied a general flame to the switch. In addition, current was supplied to the switch using the PCITS (Primary Current Injection Test System). The ambient temperature and humidity were maintained at $22{\pm}2^{\circ}C$ and 40~60% respectively while performing the test. It is thought that the switch generated heat due to a defective connection of the wire and clip, insulation deterioration and defective contact of the movable contact, etc. The surface of the switch damaged by the general flame was uniformly carbonized. When the flame source was removed, the fire on the switch was extinguished naturally. From the result obtained by disassembling the switch carbonized by the general flame, it could be seen that fixtures and movable contacts remained in comparatively good shape but the enclosure, clip support, movable contact, indicating lamp, etc. showed carbonization and discoloration. In the case of the switch damaged by overcurrent, the clip connecting the wires, clip support, etc. showed almost no trace of damage, but the fixtures, movable contact, indicating lamp, etc. were severely carbonized. That is, the sections with high contact resistance were intensively damaged and showed a damage pattern indicating that carbonization progressed from the inside to the outside. Therefore, it is possible to judge the initial energy source by analyzing the characteristics of the carbonization pattern and the metal fixtures of damaged switches.

• Journal of the Korean Institute of Gas
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• v.15 no.4
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• pp.7-14
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• 2011

Using 20 L spherical explosion vessel and differential scanning calorimeter (DSC), an experimental investigation was carried on explosion characteristics and thermal decomposition of some reactive organic dust. As the result, the minimum explosion concentration of Benzoyl peroxide (BPO), Phthalic anhydride (PA) and 1-Hydroxybenzotriazol (HBT) exist between 10 and 15 g/$m^3$, which indicates that their explosion sensitivity are high. The maximum Kst values of HBT, PA and 97 % BPO are 251, 146 and 80 [$bar{\cdot}m/s$], respectively and the explosion severity of HBT is the explosion class of St-2. The flame velocity was also calculated from the combustion time of dust and flame arrival time to estimate the flame propagation characteristics in a closed vessel. The decomposition temperature and heat of decomposition reaction for 97 % BPO and HBT are $107^{\circ}C$ (1025 J/g), $214^{\circ}C$ (1666 J/g), respectively and it was found that these low decomposition temperature and high released heat affect the explosion characteristics.